THE PURPOSE OF THE UNDERWATER SEARCH UNIT IS TO SEARCH FOR PROPERTY THROWN OR ALLEGED TO HAVE BEEN THROWN INTO THE WATER. THE FOUR-WEEK DIVING COURSE CONSISTS OF LECTURES, FILMS, AND SLIDES COVERING THE PHYSICS AND PHYSIOLOGY OF DIVING, DIVING DISEASES, DECOMPRESSION, AND SAFETY REGULATIONS. INSTRUCTION IS GIVEN IN THE USE OF SELF-CONTAINED AND SURFACE SUPPLY BREATHING EQUIPMENT. EMERGENCY DRILLS ARE PRACTICED IN INDOOR DIVING TANKS. INSTRUCTION IS GIVEN IN SEARCH TECHNIQUES AND PATTERNS, ROPE SIGNALS, AND UNDERWATER COMMUNICATIONS SYSTEMS. USE OF UNDERWATER TOOLS, LIFESAVING, RESUSCITATION, AND FIRST AID ARE ALSO TAUGHT. PRACTICE SEARCHES ARE CONDUCTED IN LOCAL WATERS. THE NORMAL GEAR WORN BY A UNIT DIVER IS A ONE-PIECE 'DRY' DIVING SUIT WITH A HOOD DESIGNED TO KEEP WATER OUT OF THE EARS. THE MASK USED IS A RELATIVELY NEW TYPE WHICH ALLOWS AIR INTO THE MASK AT A SLIGHTLY LIGHTER PRESSURE THAN THE AMBIENT WATER PRESSURE, THUS PREVENTING WATER FROM GETTING INTO THE MASK. BOTTLES CAPABLE OF TAKING PRESSURE OF ABOUT 4,500 LBS. PER SQUARE INCH ARE USED. IN BETWEEN OPERATIONAL DIVES, THE SIX MEMBERS OF THE TEAM UNDERGO A PROGRAM OF CONTINUOUS TRAINING, DURING WHICH THEY PRACTICE SEARCH PATTERNS, RESCUE TECHNIQUES, AND UNDERWATER COMMUNICATION. ALL DIVING IS DONE WITH THE DIVER ATTACHED TO A LIFELINE TO THE SURFACE. THE LIFELINE IS CALIBRATED BY COLORED TAPE SO THAT THE LIFELINE ATTENDANT ALWAYS KNOWS THE DEPTH OF THE DIVER. IT IS THROUGH THE LIFELINE THAT COMMUNICATION TAKES PLACE THROUGH 26 DIFFERENT SIGNALS USED BY THE DIVER AND ATTENDANT. PHOTOGRAPHS ARE PROVIDED. (RCB)